Mannan is a collective term for polysaccharides mainly containing mannose and is widely distributed throughout nature. Mannan includes glucomannan having a main chain formed with glucose and mannose contained in cell walls of softwood and konjac and galactomannan having a main chain formed with mannose and galactose contained in coffee beans and fruits. Because mannan exists in the form of gel, mannan is used as a thickening agent or a stabilizing agent for food products. Moreover, as mannan prevents extraction of coffee due to properties thereof, the extraction efficiency of coffee is increased by addition of mannanase (mannan decomposing enzyme).
Fungi and mushrooms secrete mannanase extracellularly to decompose mannan, thereafter intracellularly introducing and utilizing the decomposed low molecules. Various mannanases have been found so far and are utilized for manufacture of food products and industrial applications.
Mannanase generally has an optimal pH around acidic or neutral pH and an optimal temperature of around 40° C. to 70° C. Mannanases having improved heat resistance, by, for example, modification have also been reported (Patent Literature 1).